184 PALAEONTOLOGY. 



set ; the two forming the pair a\ a", again approximating in 

 the next series, and the pairs b, V and c, c', diverging in the 

 same direction and degree ; and this alternate approximation 

 and divergence is repeated throughout the entire series of the 

 present tracks. 



But what strikes tlie ichnologist, heretofore conversant 

 chiefly with the footprints of bipeds or quadrupeds, is the 

 occurrence in the present series of the third impression a, 

 which complicates the most approximated pair A, being placed 

 in front and a little to the inner side of the hindmost impres- 

 sion, a'\ of that pair. The superadded impression, a, is about 

 the same size as the innermost in each pair, the average 

 diameter of that impression being 5 lines. 



Taking this view of the impressions, it appears that whilst 

 the innermost in each pair, a', b, c, are of equal size, the outer- 

 most, a", b f , c, 1 L, progressively increase in size, from the most 

 approximated to the most divergent of the three pairs ; that 

 of the first, a", being narrow in proportion to its length, that 

 of the second, b\ as broad as long, and the outermost, c, c", of 

 the third pair being oblong, but larger than that in the first 

 pair. In some places where the most approximated pair of 

 impressions, a, a'\ are deeply marked, they are complicated by 

 a fourth shallow and very small pit, a!", 2 L, midway between 

 the third, a, and the outermost, a", of the pair of impressions. 



There are no clear or unequivocal marks of toes or nails on 

 any of the impressions which form the lateral pairs or triplets. 

 Their margins are not sharply defined, but are rounded off, and 

 sink gradually to the deepest part, which is a little behind the 

 middle of the depression. There is a slight variation in the 

 form and depth of the answerable impressions, but not such 

 as to prevent their correspondence being readily appreciable 

 through the extent of the track here described ; that is to say, 

 the innermost of each of the three pairs here described as first, 

 A, second, B, and third, C, may be identified with the corres- 



